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Topic: Horsehead gone weird (Read 148 times)

This is a stack of 20x5 minute exposures at iso 400. The processing has been done in pixinsight. I ran the sub frames through the blink comparator to get rid of gross aberrations, then through the subframe selector script to check for good quality frames and basically selected the 20 best frames in terms of star shape eccentricity and fwhm having done that I ran the remaining frames through star alignment and image integration and this is the result.

The stars are these odd bow tie shapes... now each sub frame is pretty good in terms of tracking but there is overall quite a bit of movement between the first and last frames which if you traced it out would be pretty similar to this shape but I would have expected the star alignment to have removed this?

No calibration just the light files. Interpolation was left at the default settings of Auto / 0.30 clamping threshold. Rejection method was Winsorized Sigma Clipping sigma low was 4.0 high 3.0 (again default settings)

That M101 is more illuminating. During Star Alignment are you getting any Ransac errors popping up in the console window? If so try try increasing the RANSAC tolerance to 3. If not try reducing Log (sensitivity) in the Star Detection to -2.00. It can also help to use the frame with the highest S/N ratio reported in SubFrame Selector as the reference image.

No there were no errors at all. Someone on the pixinsight forums suggested that since the images are uncalibrated the star align might be picking up noise and dead pixels as stars... So I am going to start again and calibrate with some darks from my library and see what happens..